/*
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.
 *
 * Copyright 2010 huliqing, huliqing.cn@gmail.com
 *
 * This file is part of QFaces.
 * QFaces is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * QFaces is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with QFaces.  If not, see <http://www.gnu.org/licenses/>.
 *
 * 这个文件是QFaces的一部分。
 * 您可以单独使用或分发这个文件，但请不要移除这个头部声明信息.
 * QFaces是一个自由软件，您可以自由分发、修改其中的源代码或者重新发布它，
 * 新的任何修改后的重新发布版必须同样在遵守LGPL3或更后续的版本协议下发布.
 * 关于LGPL协议的细则请参考COPYING、COPYING.LESSER文件，
 * 您可以在QFaces的相关目录中获得LGPL协议的副本，
 * 如果没有找到，请连接到 http://www.gnu.org/licenses/ 查看并获取副本。
 *
 * - Author: Huliqing
 * - Contact: huliqing.cn@gmail.com
 * - License: GNU Lesser General Public License (LGPL)
 * - Blog and source code availability: http://www.huliqing.name/
 */

package name.huliqing.qfaces.test;

import java.io.Serializable;
import java.util.List;
import javax.persistence.EntityManager;
import javax.persistence.EntityTransaction;
import javax.persistence.Query;
import name.huliqing.qfaces.model.PageParam;
 
/**
 * 
 * @author huliqing
 *
 * @param <T>
 * @param <PK>
 */
public class BaseDao<T, PK extends Serializable> {

	protected Class<T> t;
	 
	protected BaseDao(Class<T> t) {
		this.t = t;
	}
	
	public boolean delete(PK id) {
		EntityManager em = EMF.get().createEntityManager();
		EntityTransaction tx = em.getTransaction();
		try {
			tx.begin();
			T _o = em.find(t, id);
			em.remove(_o);
			tx.commit();
			return true;
		} finally {
			if (tx.isActive()) {
				tx.rollback();
				return false;
			}
			em.close();
		}
	}

	public boolean save(T t) {
		EntityManager em = EMF.get().createEntityManager();
		EntityTransaction tx = em.getTransaction();
		try {
			tx.begin();
			em.persist(t);
			tx.commit();
			return true;
		} finally {
			if (tx.isActive()) {
				tx.rollback();
				return false;
			}
			em.close();
		}
	}

	public T update(T t) {
		EntityManager em = EMF.get().createEntityManager();
		EntityTransaction tx = em.getTransaction();
		try {
			tx.begin();
			T _t = em.merge(t);
			tx.commit();
			return _t;
		} finally {
			if (tx.isActive()) {
				tx.rollback();
				return null;
			}
			em.close();
		}
	}
	
	public T find(PK id) {
		EntityManager em = EMF.get().createEntityManager();
		try {
			T _t = em.find(t, id);
			return _t;
		} finally {
			em.close();
		}
	}
	
	public List<T> findAll() {
		String className = this.t.getName();
		EntityManager em = EMF.get().createEntityManager();
		try {
			Query q = em.createQuery("select obj from " + className + " obj");
			List<T> result = q.getResultList();
			result.size();
			return result;
		} finally {
			em.close();
		}
	}
	
	public Integer findAllTotal() {
		EntityManager em = EMF.get().createEntityManager();
		String className = this.t.getName();
		try {
			Query q = em.createQuery("select count(obj) from " + className + " obj");
			Integer result = (Integer) q.getSingleResult();
			return result;
		} finally {
			em.close();
		}
	}

	// ----
	
	protected EntityManager getEM() {
		return EMF.get().createEntityManager();
	}
	
	protected Query createQuery(String hql, PageParam pp, EntityManager em) {
		StringBuilder sb = new StringBuilder(hql);
        if (pp != null) {
            if (pp.getSortField() != null)
                sb.append(" order by obj." + pp.getSortField());
            if (pp.isAsc() != null)
                sb.append(pp.isAsc() ? " asc" : " desc");
        }
        Query q = em.createQuery(sb.toString());
        if (pp != null) {
            if (pp.getStart() != null)
                q.setFirstResult(pp.getStart().intValue());
            if (pp.getPageSize() != null)
                q.setMaxResults(pp.getPageSize());
        }
        return q;
	}
}
